Radios for a trunked radio communications system may be bought inexpensively at a flea-market or on an Internet auction site and reprogrammed easily by radio programming software found on the Internet. Further, radios are often stolen and easily reprogrammed by the same software. In both cases, the reprogrammed radio may be made to work with trunked radio communications systems that operate for the Public Safety, e.g. a trunked radio communications system for the police department. Even though reprogramming radios and operating on a public safety trunked radio communications system is illegal, such activities do occur and pose a security concern.
Thus, there is a need for a new method for preventing unauthorized devices from operating in an 800 MHz trunked radio communications system using channels 559 to 320.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.